##
Bowley's data on values of British and Irish trade, 1855-1899

### Description

In one of the first statistical textbooks, Arthur Bowley (1901)
used these data to illustrate an arithmetic and graphical analysis
of time-series data using the total value of British and Irish
exports from 1855-1899. He presented a line graph of the time-series
data, supplemented by overlaid line graphs of 3-, 5- and 10-year moving
averages. His goal was to show that while the initial series
showed wide variability, moving averages made the series progressively
smoother.

### Usage

`data(Bowley)`

### Format

A data frame with 45 observations on the following 2 variables.

`Year`

Year, from 1855-1899

`Value`

total value of British and Irish exports (millions of Pounds)

### Source

Bowley, A. L. (1901). *Elements of Statistics*. London: P. S. King and Son,
p. 151-154.

Digitized from Bowley's graph.

### Examples

```
data(Bowley)
# plot the data
with(Bowley,plot(Year, Value, type='b', lwd=2,
ylab="Value of British and Irish Exports",
main="Bowley's example of the method of smoothing curves"))
# find moving averages-- use center alignment (requires width=ODD)
#require(gtools, warn.conflicts=FALSE)
# simpler version using stats::filter
running <- function(x, width = 5){as.vector(stats::filter(x, rep(1 / width, width), sides = 2))}
mav3<-running(Bowley$Value, width=3)
mav5<-running(Bowley$Value, width=5)
mav9<-running(Bowley$Value, width=9)
lines(Bowley$Year, mav3, col='blue', lty=2)
lines(Bowley$Year, mav5, col='green3', lty=3)
lines(Bowley$Year, mav9, col='brown', lty=4)
# add lowess smooth
lines(lowess(Bowley), col='red', lwd=2)
if(require("ggplot2", quietly=TRUE)) {
ggplot(aes(x=Year, y=Value), data=Bowley) +
geom_point() +
geom_smooth(method="loess", formula=y~x)
}
```